Brueckner, 49, pleaded with shop staff to sell him a handset anonymously without recording his official government ID.

He even showed a shop worker his ankle tag – but they became suspicious and told him “I know who you are,” the Sun reports.

Police in Germany are understood to be monitoring the situation.

Phone shop manager Farouk Salah-Brahmin, 32, said: “He came in and said he wanted to buy a pay-as-you-go Sim card and a smartphone.

“It was then he really weirdly asked me if he could buy a Sim card without an identity card.

“That would mean no one could trace his calls.”

The shop worker told him it’s illegal to register a phone without an ID card in Germany.

Brueckner was released last Wednesday and has been seen at a nightclub and trying to get free Domino’s pizza before he headed to the phone shop.

“Everyone hates him here. No one wants him here,” Farouk added.

Brueckner denies any involvement in the Madeleine McCann case.

He was released last week after serving a seven-year prison sentence for the rape of an elderly woman at her home in Praia da Luz in 2005.

The Met said the 49-year-old remains a suspect in its own investigation – with Portuguese and German authorities also probing Madeleine’s disappearance.

Madeleine vanished in the Portuguese resort of Praia da Luz in 2007, shortly after she was left sleeping by her parents, Kate and Gerry McCann, who went for dinner in a nearby restaurant.

Brueckner left the high-security prison in Sehnde near Hanover just after 9.15am German time (8.15am BST), last Wednesday morning, German police said.

He will have to wear an electronic ankle tag for the next five years, according to a German investigator.

Christian Wolters, prosecutor for the city of Braunschweig, said: “He will also be assigned a probation officer, with whom he must maintain contact at least once a month. Christian B must also notify the court in advance of any change of residence or place of stay and obtain its approval.

“If he violates these conditions, he faces either a fine or a prison sentence of up to three years.”

German media also reported that he will have to give up his passport, although his lawyers are expected to appeal against the conditions.

Prosecutors still believe Brueckner was responsible for the girl’s disappearance, and Mr Wolters said Brueckner’s release from prison has “no direct impact” on the probe.

“The release of Christian B has no direct impact on the McCann case,” Mr Wolters added.

Brueckner has not been charged in the case, in which he is under investigation on suspicion of murder.

He has previously denied any involvement in her disappearance.

Authorities also say he is still dangerous, following a recent psychiatric report that concluded he is likely to commit further crimes after he failed to undergo any therapy while in custody, according to reports.

A court hearing is also listed for October 27 in Oldenburg in north-west Germany, to deal with a case in which he is accused of insulting a prison employee.

Earlier this week, the Metropolitan Police said it had sent an international letter of request to 49-year-old German national Brueckner for him to speak with them upon his release, which he later rejected.

Force chief Sir Mark Rowley said that the British investigation into the disappearance of Madeleine remains a missing person inquiry.

He told journalists that the force is “taking stock” of the German and Portuguese investigations now that the prime suspect Brueckner has walked free from prison.

“He remains a suspect for us. We are taking stock of where we are, and the German investigation and the Portuguese investigation,” Sir Mark said.

A number of searches have been carried out by German, Portuguese and British authorities since Madeleine’s disappearance – with the latest taking place near the Portuguese municipality of Lagos in June.

In 2023, investigators carried out searches near the Barragem do Arade reservoir, about 30 miles from Praia da Luz.

Brueckner spent time in the area between 2000 and 2017 and had photographs and videos of himself near the reservoir.

In October last year, the suspect was cleared by a German court of unrelated sexual offences, alleged to have taken place in Portugal between 2000 and 2017.

The total funding given to the Met’s investigation, titled Operation Grange, has been more than £13.2 million since 2011 after a further £108,000 was secured from the Government in April.